1. Field of Invention
The field of the present invention relates in general to wireless local area networks (WLAN) including wireless access points (WAP) and stations and methods of matrix processing thereon.
2. Description of the Related Art
Home and office networks, a.k.a. wireless local area networks (WLAN) are established using a device called a Wireless Access Point (WAP). The WAP may include a router. The WAP wirelessly couples all the devices of the home network, e.g. wireless stations such as: computers, printers, televisions, digital video (DVD) players, security cameras and smoke detectors to one another and to the Cable or Subscriber Line through which Internet, video, and television is delivered to the home. Most WAPs implement the IEEE 802.11 standard which is a contention based standard for handling communications among multiple competing devices for a shared wireless communication medium on a selected one of a plurality of communication channels. The frequency range of each communication channel is specified in the corresponding one of the IEEE 802.11 protocols being implemented, e.g. “a”, “b”, “g”, “n”, “ac”, “ad”. Communications follow a hub and spoke model with a WAP at the hub and the spokes corresponding to the wireless communication links to each ‘client’ device.
After selection of a single communication channel for the associated home network, access to the shared communication channel relies on a multiple access methodology identified as Collision Sense Multiple Access (CSMA). CSMA is a distributed random access methodology first introduced for home wired networks such as Ethernet for sharing a single communication medium, by having a contending communication link back off and retry access to the line if a collision is detected, i.e. if the wireless medium is in use.
Multiple-Input Multiple-Output (MIMO) equipped WAPs and stations have been gaining in popularity due to their ability to provide increased performance without the need to increase bandwidth and power. In a MIMO system, both transmitter and receiver have multiple antennas. This creates a matrix channel between the signals coming out of the transmit antennas and the signals observed at the receiver antennas. Where, as in a home or office, the environment has sufficiently rich signal scattering the MIMO system will support simultaneous independent data streams which increases throughput.
MIMO systems use Orthogonal Frequency Division Multiplexing (OFDM). OFDM divides the bandwidth of the signal into a relatively high number of orthogonal narrowband channels or “tones”. The advantage is that channel estimation and equalization can be performed independently on each of the narrow-band channels. Since the channel for each tone is now a matrix, many of the channel operations that need to be performed now require matrix manipulation. These operations are most efficiently implemented in dedicated hardware, because they need to be performed very frequently and at high speed.
Communications on the single communication medium are identified as “simplex” meaning, communications from a single source node to one target node at one time, with all remaining nodes capable of “listening” to the subject transmission. Starting with the IEEE 802.11ac standard and specifically ‘Wave 2’ thereof, discrete communications to more than one target node at the same time may take place using what is called Multi-User (MU) MIMO capability of the WAP.
The IEEE 802.11ac standard also opened up new channel bandwidths, up to 160 MHz in a new Wi-Fi frequency range, i.e. 5 GHz. An IEEE 802.11 compliant wireless local area network (WLAN) utilizes many discrete contiguous narrow band sub-channels, sub-carriers or tones to support broadband communications on the selected communication channel. This scheme is referred to as orthogonal frequency-division multiplexing (OFDM). Each tone is independently modulated and requires considerable overhead in terms of processing and communication between transmitter and receiver to adequately set up and characterize one or more communication links thereon. An IEEE 802.11ac compliant WAP or station may, for example, be required to process up to 512 independent sub-carriers or tones at its full 160 MHz bandwidth.
Each revision of the IEEE 802.11 standard, offers enhanced capabilities and capacity. These capabilities come at a price in terms of increased overhead and processing capability.
What is needed are improved methods for managing processing of WLAN communications on individual tones/sub-carriers.